I totaled up the cost for just a case (complete silk screened top, bottom, sides, front and rear) and it would run about $350, the knobs would be about $75. Also note that since the case has large holes for the knobs, the standard x0xb0x knobs wouldn't really work.
The other parts such as PCB standoffs, LED standoffs, waveform switch, etc could be sourced independently.
The modifications that need to be made would be putting all of the switches on a riser (I used some plastic squares) and bending the switch legs so they are longer. Then you would also need to replace all of the LED risers so they sit higher. The waveform switch should also be replaced, I used a different model from the same company that was a bit taller. If you don't raise all of the components, the knobs will sit about 3mm higher on the case and look a bit strange. I think someone else used the same type of knob before, and they sit very high.
Also, the boards sit right on top of each other in the case, so you need to make sure that the large caps in the power supply can nest in right where the LA4140 is on the main board. This also means there no room in the back to add any mods, although there is plenty of space towards the front of the case.
Once the case is assembled, I seal the edges so it feels more solid, otherwise you get a little rattle from the panels.